summaryrefslogtreecommitdiff
path: root/arch/sparc/kernel/unaligned_32.c
blob: f8514e291e1559ecda6994ff5be883cc6805128c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
/*
 * unaligned.c: Unaligned load/store trap handling with special
 *              cases for the kernel to do them more quickly.
 *
 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
 * Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
 */


#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <asm/ptrace.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/perf_event.h>

enum direction {
	load,    /* ld, ldd, ldh, ldsh */
	store,   /* st, std, sth, stsh */
	both,    /* Swap, ldstub, etc. */
	fpload,
	fpstore,
	invalid,
};

static inline enum direction decode_direction(unsigned int insn)
{
	unsigned long tmp = (insn >> 21) & 1;

	if(!tmp)
		return load;
	else {
		if(((insn>>19)&0x3f) == 15)
			return both;
		else
			return store;
	}
}

/* 8 = double-word, 4 = word, 2 = half-word */
static inline int decode_access_size(unsigned int insn)
{
	insn = (insn >> 19) & 3;

	if(!insn)
		return 4;
	else if(insn == 3)
		return 8;
	else if(insn == 2)
		return 2;
	else {
		printk("Impossible unaligned trap. insn=%08x\n", insn);
		die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
		return 4; /* just to keep gcc happy. */
	}
}

/* 0x400000 = signed, 0 = unsigned */
static inline int decode_signedness(unsigned int insn)
{
	return (insn & 0x400000);
}

static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
				       unsigned int rd)
{
	if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
		/* Wheee... */
		__asm__ __volatile__("save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "restore; restore; restore; restore;\n\t"
				     "restore; restore; restore;\n\t");
	}
}

static inline int sign_extend_imm13(int imm)
{
	return imm << 19 >> 19;
}

static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
{
	struct reg_window32 *win;

	if(reg < 16)
		return (!reg ? 0 : regs->u_regs[reg]);

	/* Ho hum, the slightly complicated case. */
	win = (struct reg_window32 *) regs->u_regs[UREG_FP];
	return win->locals[reg - 16]; /* yes, I know what this does... */
}

static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
{
	struct reg_window32 __user *win;
	unsigned long ret;

	if (reg < 16)
		return (!reg ? 0 : regs->u_regs[reg]);

	/* Ho hum, the slightly complicated case. */
	win = (struct reg_window32 __user *) regs->u_regs[UREG_FP];

	if ((unsigned long)win & 3)
		return -1;

	if (get_user(ret, &win->locals[reg - 16]))
		return -1;

	return ret;
}

static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
{
	struct reg_window32 *win;

	if(reg < 16)
		return &regs->u_regs[reg];
	win = (struct reg_window32 *) regs->u_regs[UREG_FP];
	return &win->locals[reg - 16];
}

static unsigned long compute_effective_address(struct pt_regs *regs,
					       unsigned int insn)
{
	unsigned int rs1 = (insn >> 14) & 0x1f;
	unsigned int rs2 = insn & 0x1f;
	unsigned int rd = (insn >> 25) & 0x1f;

	if(insn & 0x2000) {
		maybe_flush_windows(rs1, 0, rd);
		return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
	} else {
		maybe_flush_windows(rs1, rs2, rd);
		return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
	}
}

unsigned long safe_compute_effective_address(struct pt_regs *regs,
					     unsigned int insn)
{
	unsigned int rs1 = (insn >> 14) & 0x1f;
	unsigned int rs2 = insn & 0x1f;
	unsigned int rd = (insn >> 25) & 0x1f;

	if(insn & 0x2000) {
		maybe_flush_windows(rs1, 0, rd);
		return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
	} else {
		maybe_flush_windows(rs1, rs2, rd);
		return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
	}
}

/* This is just to make gcc think panic does return... */
static void unaligned_panic(char *str)
{
	panic(str);
}

/* una_asm.S */
extern int do_int_load(unsigned long *dest_reg, int size,
		       unsigned long *saddr, int is_signed);
extern int __do_int_store(unsigned long *dst_addr, int size,
			  unsigned long *src_val);

static int do_int_store(int reg_num, int size, unsigned long *dst_addr,
			struct pt_regs *regs)
{
	unsigned long zero[2] = { 0, 0 };
	unsigned long *src_val;

	if (reg_num)
		src_val = fetch_reg_addr(reg_num, regs);
	else {
		src_val = &zero[0];
		if (size == 8)
			zero[1] = fetch_reg(1, regs);
	}
	return __do_int_store(dst_addr, size, src_val);
}

extern void smp_capture(void);
extern void smp_release(void);

static inline void advance(struct pt_regs *regs)
{
	regs->pc   = regs->npc;
	regs->npc += 4;
}

static inline int floating_point_load_or_store_p(unsigned int insn)
{
	return (insn >> 24) & 1;
}

static inline int ok_for_kernel(unsigned int insn)
{
	return !floating_point_load_or_store_p(insn);
}

static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
{
	unsigned long g2 = regs->u_regs [UREG_G2];
	unsigned long fixup = search_extables_range(regs->pc, &g2);

	if (!fixup) {
		unsigned long address = compute_effective_address(regs, insn);
        	if(address < PAGE_SIZE) {
                	printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
        	} else
                	printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
	        printk(KERN_ALERT " at virtual address %08lx\n",address);
		printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n",
			(current->mm ? current->mm->context :
			current->active_mm->context));
		printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n",
			(current->mm ? (unsigned long) current->mm->pgd :
			(unsigned long) current->active_mm->pgd));
	        die_if_kernel("Oops", regs);
		/* Not reached */
	}
	regs->pc = fixup;
	regs->npc = regs->pc + 4;
	regs->u_regs [UREG_G2] = g2;
}

asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
{
	enum direction dir = decode_direction(insn);
	int size = decode_access_size(insn);

	if(!ok_for_kernel(insn) || dir == both) {
		printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n",
		       regs->pc);
		unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
	} else {
		unsigned long addr = compute_effective_address(regs, insn);
		int err;

		perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, 0, regs, addr);
		switch (dir) {
		case load:
			err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
							 regs),
					  size, (unsigned long *) addr,
					  decode_signedness(insn));
			break;

		case store:
			err = do_int_store(((insn>>25)&0x1f), size,
					   (unsigned long *) addr, regs);
			break;
		default:
			panic("Impossible kernel unaligned trap.");
			/* Not reached... */
		}
		if (err)
			kernel_mna_trap_fault(regs, insn);
		else
			advance(regs);
	}
}

static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
			      enum direction dir)
{
	unsigned int reg;
	int check = (dir == load) ? VERIFY_READ : VERIFY_WRITE;
	int size = ((insn >> 19) & 3) == 3 ? 8 : 4;

	if ((regs->pc | regs->npc) & 3)
		return 0;

	/* Must access_ok() in all the necessary places. */
#define WINREG_ADDR(regnum) \
	((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))

	reg = (insn >> 25) & 0x1f;
	if (reg >= 16) {
		if (!access_ok(check, WINREG_ADDR(reg - 16), size))
			return -EFAULT;
	}
	reg = (insn >> 14) & 0x1f;
	if (reg >= 16) {
		if (!access_ok(check, WINREG_ADDR(reg - 16), size))
			return -EFAULT;
	}
	if (!(insn & 0x2000)) {
		reg = (insn & 0x1f);
		if (reg >= 16) {
			if (!access_ok(check, WINREG_ADDR(reg - 16), size))
				return -EFAULT;
		}
	}
#undef WINREG_ADDR
	return 0;
}

static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
{
	siginfo_t info;

	info.si_signo = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRALN;
	info.si_addr = (void __user *)safe_compute_effective_address(regs, insn);
	info.si_trapno = 0;
	send_sig_info(SIGBUS, &info, current);
}

asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
{
	enum direction dir;

	lock_kernel();
	if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) ||
	   (((insn >> 30) & 3) != 3))
		goto kill_user;
	dir = decode_direction(insn);
	if(!ok_for_user(regs, insn, dir)) {
		goto kill_user;
	} else {
		int err, size = decode_access_size(insn);
		unsigned long addr;

		if(floating_point_load_or_store_p(insn)) {
			printk("User FPU load/store unaligned unsupported.\n");
			goto kill_user;
		}

		addr = compute_effective_address(regs, insn);
		perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, 0, regs, addr);
		switch(dir) {
		case load:
			err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
							 regs),
					  size, (unsigned long *) addr,
					  decode_signedness(insn));
			break;

		case store:
			err = do_int_store(((insn>>25)&0x1f), size,
					   (unsigned long *) addr, regs);
			break;

		case both:
			/*
			 * This was supported in 2.4. However, we question
			 * the value of SWAP instruction across word boundaries.
			 */
			printk("Unaligned SWAP unsupported.\n");
			err = -EFAULT;
			break;

		default:
			unaligned_panic("Impossible user unaligned trap.");
			goto out;
		}
		if (err)
			goto kill_user;
		else
			advance(regs);
		goto out;
	}

kill_user:
	user_mna_trap_fault(regs, insn);
out:
	unlock_kernel();
}